Results of P-3 spin 7G pull out

[transpac]

Its been a while since i read the report, but 7g's sounds high- IIRC it being more in the 5 range. The FE, on his own, did in fact restart the shutdown engine while in the high speed spiral- thats what saved the crew!

If this was a high speed spiral, why couldn't they recover with rudder and aileron? I heard it was in fact a developed spin and the high g loads were acheived during recovery.

 

[zippy]

If this was a high speed spiral, why couldn't they recover with rudder and aileron? I heard it was in fact a developed spin and the high g loads were acheived during recovery.

I've heard both terms used to describe the event.
Looking at what is in the article, they use the term spiral.

Not being able to recover with rudder and aileron probably had something to do with Engines #3 and #4 being left at max power during their trip towards the water.

 

[pilotyip]

Spinning the P-3

My PPC in 1968 had been a test pilot at Pax River and did the initial fleet testing of the P-3's back in 1961. He was a graduate of hte Navy Test Pilot School at Pax River. He was on a flight with a Lockheed test pilot doing dynamic stability testing. This is where you trim the airplane up in level steady state flight at FL200 and watch it oscillate. Well on one oscillation it went nearly vertical and flipped on its back and started spinning. He said them used every technique know in spin recovery and nothing worked, coming out of 8,000' the airplane flew out of the spin. They went back studied the aero dynamics of the spin and decided they could recover using a certain technique, the next week they repeated the event, got the same results with the new procedures. They elected not to spin the P-3 again. As a result spins were prohibited in the P-3. It is interesting that as the air became more dense, the P-3 became more controlable. BTW he also trained Flatly to fly the C-130 so he could make his landings in the C-130 on an aircraft carrier.

 

[transpac]

I've heard both terms used to describe the event.
Looking at what is in the article, they use the term spiral.

Not being able to recover with rudder and aileron probably had something to do with Engines #3 and #4 being left at max power during their trip towards the water.

Makes sense that bringing #1 back online could result in a kind of back-door way to recover from a spin, but not a high speed spiral. I don't know the two-engine Vmca on the P3, but remember that it was in the neighborhood of 140 kts on the C-130. In any event, a high-speed spiral with two engines out would seem to be recoverable even with the effects of assymetrical thrust. If they were in a spiral, the recovery credit being given to the engine restart mystifies me for a couple of reasons: The immediate effect of bringing the engine out of feather for an airstart would have increased the drag on the left side significantly and tightened the spiral. (I remember a figure of about 20,000 HP being extracted from the airstream to windmill an engine at 100%. The T-56 does not produce positive HP until its onspeed at 100%) Second, with two engines at max power and heading down at high speed, the last thing needed is another engine at max power.

There's an article in Approach magazine about a similar incident many years ago. But, this crew did everything right during the recovery.

http://www.safetycenter.navy.mil/media/approach/issues/novdec05/pdf/We_Just_Spun.pdf

 

[zippy]

Makes sense that bringing #1 back online could result in a kind of back-door way to recover from a spin, but not a high speed spiral. I don't know the two-engine Vmca on the P3, but remember that it was in the neighborhood of 140 kts on the C-130. In any event, a high-speed spiral with two engines out would seem to be recoverable even with the effects of assymetrical thrust. If they were in a spiral, the recovery credit being given to the engine restart mystifies me for a couple of reasons: The immediate effect of bringing the engine out of feather for an airstart would have increased the drag on the left side significantly and tightened the spiral. (I remember a figure of about 20,000 HP being extracted from the airstream to windmill an engine at 100%. The T-56 does not produce positive HP until its onspeed at 100%) Second, with two engines at max power and heading down at high speed, the last thing needed is another engine at max power.

There's an article in Approach magazine about a similar incident many years ago. But, this crew did everything right during the recovery.

http://www.safetycenter.navy.mil/media/approach/issues/novdec05/pdf/We_Just_Spun.pdf

Very interesting article. That explains why ditching drills are conducted at the altitude they are. I always wondered..

Like I said, I've seen both terms used (interchangebly) to describe the event in products put out by our community. The article in the news used spiral so I went with that.

 

[transpac]

He was on a flight with a Lockheed test pilot doing dynamic stability testing. This is where you trim the airplane up in level steady state flight at FL200 and watch it oscillate. Well on one oscillation it went nearly vertical and flipped on its back and started spinning. He said them used every technique know in spin recovery and nothing worked, coming out of 8,000' the airplane flew out of the spin.

Sounds like they were doing a longitudinal stability test by inducing phugoids. If so, it's surprising the Navy didn't require a horizontal stab modification to increase stability. The FAA requires the amplitude of the pitch cycles to decrease without pilot input and the airplane to eventually return to stabilized flight.

 

[b707guy]

Nothing like positive dynamic stability to keep you warm and fuzzy. That's an interesting article - thanks for the link! On a side note, I'm glad they spelled out what "PUI" meant. Sounds too close to "DUI" for the overly imaginative such as myself...

 

[Oh-ryan]

Makes sense that bringing #1 back online could result in a kind of back-door way to recover from a spin, but not a high speed spiral. I don't know the two-engine Vmca on the P3, but remember that it was in the neighborhood of 140 kts on the C-130. In any event, a high-speed spiral with two engines out would seem to be recoverable even with the effects of assymetrical thrust. If they were in a spiral, the recovery credit being given to the engine restart mystifies me for a couple of reasons: The immediate effect of bringing the engine out of feather for an airstart would have increased the drag on the left side significantly and tightened the spiral. (I remember a figure of about 20,000 HP being extracted from the airstream to windmill an engine at 100%. The T-56 does not produce positive HP until its onspeed at 100%) Second, with two engines at max power and heading down at high speed, the last thing needed is another engine at max power.

There's an article in Approach magazine about a similar incident many years ago. But, this crew did everything right during the recovery.

http://www.safetycenter.navy.mil/media/approach/issues/novdec05/pdf/We_Just_Spun.pdf

Good article. I like the editor's comment that the most important aspect of the incident was that it was actually reported. The editor even complimented the IP on admitting his "goof". Like the IP even had a choice but to report that incident. There is no way the FE or aft observer would have been able to keep that secret. The story would have spread through the AW shop faster than the clap does on deployment.

 

[MasterOfYaw]

Thanks for the responses! I guess I'll have to take a Mythbusters "plausible" verdict, then. At the same time, I'd figure 5.5gs in a hurricane would most likely be brought on by wind shear in addition to elevator, not flight control input alone. The report did say the 7gs was experienced in a roll, and asymmetric load limits are usually less than symmetric. Also, most ultimate load limits are set at 150% of the design limit, so with a 3g operational limit, the ultimate limit (where structure should fail outright, not just pop rivets and crack spars) should be around 4.5gs. Regardless, I'd say that's one lucky crew that they're all still with us. The photos of the damage are pretty amazing.

Here's an article on the Hugo P-3:

One tough birdie – a bumpy WP-3D ride into hurricane Hugo
as published in Lockheed’s “Airborne Log” of May 1990

14 September 1988, Barbados, West Indies. NOAA WP-3D aircraft N42RF and N43RF departed home base at Miami International and set course for Grantly Adams International on the island of Barbados to establish an operational base. At their evening arrival they were met by a local reporter, The Nation Newspaper's Janice Griffith, who had been approved to ride along and wanted to confirm her seat on the first flight into Hugo.

15 September 1988, Grantly Adams International. Just before noon, Janice arrived at the airport and met Program Coordinator Dr. James McFadden. Dr. McFadden spent some time trying to explain what Janice was getting into. Janice wasn't fazed. Hugo was about an hour east. Two NOAA P-3s Would work the storm together; an Air Force WC-130 would also be working, but higher. N42RF with Janice aboard would enter the eye at 1500'. N43RF would work the perimeter at 20,000'. Flight crew was typical for a hurricane hunt: Pilot Gerry McKim, Co-Pilot Lowell Genzlinger, Flight Director Jeff Masters, NAV Sean White, Flight Engineer Steve Wade. The tactical crew consisted of Hurricane Program Manager Dr. James McFadden, Meteorologists Drs. Pete Black, Bob Burpee, Frank Marks, Hugh Willoughby and Peter Dodge. Terry Schrickner and Alan Goldstein served as electronics engineers while Neil Rain was the electronics technician. On the radio was Tom Nunn.

14.6 degrees north, 54.6 degrees west. NOAA 42 was at 1500' anticipating entry into the eye of Hugo. Janice had strapped in securely and the plane was as ready as ever. This would be copilot Lowell Genzlinger's 249th eye penetration. Janice was taking notes as well as possible in the constant buffeting; she observed the WP-3D was in its 14th year and the time was 1:28 p.m. As the plane was about to enter the eye, the sky grew dark and Janice set aside her pen. Later she filled in with the following, "All hell seemed to break loose around me. Briefcases, cups, soda cans, books, anything unsecured came clattering down. I just gripped the nearest arm and held on for dear life." Though not familiar with the norm, Janice had properly recognized an aircraft out of control. According to Pilot Gerry McKim, the plane was doing what it wanted. Nothing they did changed anything. Full aileron one way and the plane went the other. For an eternal two min utes, their fate was unknown. The beating they were taking was as bad as anything the team had ever experienced. A crash in the cabin was the sound of a life raft breaking loose and nearly puncturing the ceiling. The rain pounding against the fuselage was deafening. The instruments were unreadable. Both pilots fought back with all their might.

Number three engine at this point overheated to 1260 degrees, torched and was shutdown. Suddenly the sky cleared to the right. The pilots forced the plane toward the clearing, starboard into the bad engine. The aircraft lurched and dropped 800 feet in 20 seconds. Desperately, the flight crew started dumping fuel and expendables as fast as they could to halt the descent. The radar attitude was about 700 feet over a boiling ocean of 65 foot waves. The turn into the clear and quick action by the flight crew paid off at last. They had entered the eye and were able to get the aircraft back under control. The diameter was 8 miles -a tight one. Pilots McKim and Genzlinger began a slow climbing turn to regain their lost altitude, while in an eye that offered little reprieve from the turbulence. They had many concerns, but getting out seemed to override the fact that they had to abort the mission; they would not meet their objectives. This sortie's eight planned penetrations at different altitudes would yield no data. But as meteorologist Bob Burpee pointed out, getting the crew back was their first objective.

The Air Force WC-130 was called for assistance. After 17 turns now at 7000' on the radar altimeter, the crew noticed a weak area in the eight mile thick eye wall. The Air Force WC-130 would check it out for them. Soon the P-3 was following the WC-130 through the soft NE side of the wall. N43RF and the WC-130 were checking 42 for visible signs of damage. "There was a real mess in the back," Genzlinger remarked. "All the drawers were out and everything was scattered. The G meter read -3.5 to + 5.6. We'd never seen anything like it and never want to go through that again." Both planes headed back to Barbados. Only N43RF continued flying missions on Hugo.

After defying what may be the worst beating a P-3 bas ever taken, N42RF was cleared for 3-engine ferry back to Florida by an inspection team out of NAS Jacksonville. The airplane was scheduled for SDLM the following months; NOAA decided to send it off early. Maintenance determined that fuel control temperature sensor failure caused the overtemp. Later they found no new cracks that could be attributed to the violent entry into Hugo's eye. A normal SDLM for the aircraft's age and hours was scheduled. The G-meters were checked for accuracy because of the unbelievable readings. The +5.6 was correct. The -3.4 should have read -3.9! The WP-3D is rated for + 2.5 and -1, so the only explanation for the wings remaining intact is the instantaneousness of the blow and the probability that the force occurred far forward in the fuselage. With the P-3's monocoque design, the forward fuselage acts like a giant spring. Also, the aircraft was rarely in a straight and level position during the worst turbulence. Copilot Lowell Ginzlinger's memento of the now famed Hugo flight tells a horrendous story. In a 30 second period, the vertical wind changed from + 45 knots to -20 knots, and flight level winds changed from 190 knots to 50 knots. The aircraft lost 700 feet of altitude, and pressure dropped to the all-time Hugo low of 915 mb; lower than the central eye pressure by 15 mb. The crew had never experienced such a ravaged interior. In retrospect they concluded that strong sideloading during the unprecedented attitudes and G-forces accounted for the difference. The NOAA teams' biggest regret (besides being on the flight) was that N42RF was sent off to SDLM when a simple fuel control change would have made it capable of more flights into Hugo.

I do remember at least some if not all of the accelerometers being fairly far forward in the aircraft, so it is possible the readings published were quite different than the loads experienced by the wing and tail assembly.

MofY

P.S. I remember 2 engine Vmcair being 145 kts. I flew P-3's from 89-95 and do not recall practicing 2 engine ditches. Ditching speed was well below 145, so perhaps we learned our lesson. We did practice stalls in the airplane, but always 4 engine. There was plenty of buffet margin before the plane would depart, and recovery was docile as long as you were smooth with the power.

 

[pilotyip]

don't remember everything

Sounds like they were doing a longitudinal stability test by inducing phugoids. If so, it's surprising the Navy didn't require a horizontal stab modification to increase stability. The FAA requires the amplitude of the pitch cycles to decrease without pilot input and the airplane to eventually return to stabilized flight.

It was one of those time killers you do in the cockpit while on Patrol. The PPC talked about his flight testing of the P-3 back in 1961-62. They did diffferent weights, different CG's so I don't know what configuration they were in when he got it on its back. I also remember him talking about the testing of the 142K (MGTOW) 3 eng abort, they would land at that weight 37K over MLW and do the abort on three enignes.